Can I upload a single before my album, and then include that single on my album?

Yes! 

You can publish some songs before the whole album launch as a single format.

Just upload the single first, and then upload the entire album (including the single) as a separate release. 

When creating the album, You will have the option to select tracks already distributed (as singles) from your catalogue (to maintain the same ISRC codes) and the option to add the new ones from your computer. 

Once the full release is in stores, you can choose to leave the single, or remove it and only have the album version available.